Canvas and other like fabrics are often used to provide protection against the elements. For many products, these are the materials of choice for two reasons: first, they are effective in providing a shield from the natural elements including wind, rain, snow and sun; and secondly, by virtue of the soft, resilient nature of these materials, they are flexible and compactible which allows for their convenient retraction and storage. Tents and awnings, for example, have historically been manufactured from canvas because of the protection it provides, and because such canvas products may be readily folded and stored when not in use.
Vehicle covers have also been fabricated from canvas-like materials for many of the same reasons. Folding tops for automobiles provide the benefits that a convertible automobile affords. However, during periods of cool or inclement weather, the driver is fully protected by the automobile's convertible roof in its engaged position. Boaters may enjoy similar protection provided by analogous covers. In addition to protection against sun, wind and rain, boaters may also rely on these covers for protection of the vessel's occupants and interior against sea water during stormy or high sea conditions. For safety reasons, in addition to providing protection against the elements, vehicle and boat covers must also provide visibility to the operator. Typically, transparent sections are incorporated into automobile convertible tops (e.g., rear windows), as well as boat enclosures (such as a sailboat storm dodger). These windows also provide viewing for passengers within the vehicle or boat.
Windows are typically made from glass. However, because glass is inflexible and unable to absorb shock, its utility as a window material in a flexible, compactible protective enclosure is greatly diminished. Alternatives to glass primarily include flexible, resinous materials (i.e., plastics). Clear vinyl is one such plastic which has been widely used as transparent sections or windows in these applications. Despite its widespread application, vinyl does not share the ideal transparency properties of glass. Over time and use, wrinkles form in the vinyl which reduce its visibility. Vinyl transparency is further diminished by the difficulty associated with its cleaning. In addition, vinyl sections are susceptible to changes in size and shape as a result of heating and cooling cycles which are commonly encountered in normal use of these materials as windows.
Perhaps the most durable plastics which maintain high visibility are semi-rigid Plexiglas-type materials. These materials are characterized by high transparency, ease of cleaning, and high shock resistance. Typical of this type of material are polycarbonate and acrylic-based thermoplastic sheets.
The primary difficulty in manufacturing a suitable protective cover with a transparent section lies in the formation of a suitable adherence or bond between the flexible protective material (e.g., the canvas) and the semi-rigid transparent section (e.g., the Plexiglas). This difficulty results from the difference in the nature of the two materials. Canvas and other like fabrics are woven or otherwise composed of fibers, and possess a porous, rough and non-uniform surface. On the other hand, typical transparent sections are resinous materials with a relatively smooth and uniform surface.
Previous methods of joining such divergent materials include mechanical techniques, such as securing a transparent section in a fabric frame and attaching the frame to the body of the covering through the use of pins (U.S. Pat. No. 3,241,877). Attempts have also been made to secure transparent sections in rigid frames (U.S. Pat. No. 5,121,703). Alternatively, vinyl transparent sections have often been sewn to the flexible portion of the covering (U.S. Pat. No. 5,027,739). In these instances, the interface between the flexible protective sheet and the transparent section is troublesome. Merely securing the window in a fabric provides no seal against the natural elements. Moreover, the seam which results from sewing the two materials is susceptible to both leakage and eventual breakdown and tearing.
Accordingly, there is a need in the art for a method for adhering canvas and like fabrics to semi-rigid transparent materials to provide flexible, protective coverings with high transparency. Furthermore, such a method should provide a durable bond between the two materials without the disadvantages associated with existing mechanical attachment techniques. The present invention fulfills these needs, and provides further related advantages.